Science China Materials最新文献

Sodium metal batteries are emerging as promising energy storage technologies owing to their high-energy density and rich resources. However, the challenge of achieving continuous operation at high areal capacity hinders the application of this system. Here, a robust two-dimensional tin/sodium–tin alloy interface was introduced onto an Al substrate as an anode via an industrial electroplating strategy. Unlike the widely accepted in situ formation of Na₁₅Sn₄ alloys, the formation of Na₉Sn₄ alloys results in a semi-coherent interface with sodium due to low lattice mismatch (20.84%), which alleviates the lattice stress of sodium deposition and induces subsequent dense sodium deposition under high areal capacity. In addition, the strong interaction of Sn with anions allows more PF₆⁻ to preferentially participate in the interfacial solvation structure, thereby facilitating the formation of a thin (10 nm) NaF-rich solid electrolyte interface. Therefore, the substrate can withstand a high areal capacity of 5 mA h cm⁻², exhibiting a high average Coulombic efficiency of 99.7%. The full battery exhibits long-term cycling performance (600 cycles) with a low decay rate of 0.0018% per cycle at 60 mA g⁻¹.

Carbon-based anode materials are widely used in various battery energy storage systems due to their low cost, wide source, high conductivity and easy morphology control. However, current commercially available anode materials as active materials for lithium-/sodium-ion batteries generally suffer from large volume changes and poor rate performance. In response, we synthesized defect-rich N, S co-doped two dimensional (2D) nanosheet-assembled porous carbon microspheres (N, S-PCS) via simple hydrothermal, carbonization and etching process based on the principle of Schiff base reaction. The N, S-PCS structure is thus constructed by removing Fe₇S₈ nanoparticles from the carbon skeleton to form porous microspheres with N, S doping. Therefore, the micromorphology characteristic, pore structure and electro-conductivity of carbon materials are effectively optimized via heteroatom doping and surface engineering. As expected, the prepared N, S-PCS electrodes exhibit excellent electrochemical performance in both lithium-ion and sodium-ion batteries. For lithium-ion batteries, it achieves reversible capacities of 1045 and 237 mAh g⁻¹ at 0.1 and 20 A g⁻¹, respectively. For sodium-ion batteries, it shows good cycling stability with a capacity of 157 mAh g⁻¹ after 500 cycles at 1 A g⁻¹. Experimental and theoretical calculation results confirm that the N, S co-doping strategies help to improve the structural stability, shorten the ion diffusion paths, and promote the reaction kinetics, thus achieving excellent electrochemical performance. This work is instructive for the practical application of nonmetal doping functionalized porous carbon structures for metal-ion batteries.

Embedded phase-change random-access memory (ePCRAM) applications demand superior data retention in amorphous phase-change materials (PCMs). Traditional PCM design strategies have focused on enhancing the thermal stability of the amorphous phase, often at the expense of the crystallization speed. While this approach supports reliable microchip operations, it compromises the ability to achieve rapid responses. To address this limitation, we modified ultrafast-crystallizing Sb thin films by incorporating Sc dopants, achieving the highest 10-year retention temperature (∼175°C) among binary antimonide PCMs while maintaining a sub-10-ns SET operation speed. This reconciliation of two seemingly contradictory properties arises from the unique kinetic features of the 5-nm-thick Sc₁₂Sb₈₈ films, which exhibit an enlarged fragile-to-strong crossover in viscosity at medium supercooled temperature zones and an incompatible sublattice ordering behavior between the Sc and Sb atoms. By tailoring the crystallization kinetics of PCMs through strategic doping and nanoscale confinement, we provide new opportunities for developing robust yet swift ePCRAMs.

Two new thermally activated delayed fluorescence (TADF) molecules, 13-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine (BOBT) and 13-(4-(dimesitylboranyl)-3,5-dimethylphenyl)-5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine (BPBT), are constructed via connecting the 5,5-dimethyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine (BTDMAC) donor (D) with triarylboron or oxygen-bridged cyclized boron acceptors (A), respectively. In comparison with the photoluminescence quantum yield (PLQY) of 84% for BPBT, BOBT shows a higher PLQY of 100%, due to the multi-resonance effect of the boron-oxygen skeleton. In addition, the D-A-type molecular structural characteristic endows the boron-containing BOBT emitter with a fast reverse intersystem crossing rate on the order of 10⁶ s⁻¹. The sky-blue organic light-emitting diode (OLED) employing the BOBT emitter achieves state-of-the-art device performances with a high external quantum efficiency of 32.6%.

Antimony sulfide (Sb₂S₃) solar cells fabricated via hydrothermal deposition have attracted widespread attention. The annealing crystallization process plays a crucial role in achieving optimal crystallinity in hydrothermal Sb₂S₃ thin films. Nevertheless, incomplete crystallization and the loss of sulfur at high-temperature contribute to defect recombination, constraining device performance. Herein, a two-step rapid thermal processing (RTP) annealing strategy is proposed to improve the crystal quality and efficiency of Sb₂S₃ solar cells. The annealing process in Ar protection with atmospheric pressure can suppress S loss caused by saturated vapor pressure. The two-step RTP annealing with the 330°C low-temperature and 370°C high-temperature process ensures high crystallinity and vertical orientations of Sb₂S₃ thin films, accompanied by a reduction in defect concentration from 1.01 × 10¹² to 5.97 × 10¹¹ cm⁻³. The Sb₂S₃ solar cell achieves an efficiency of 8.20% with an enhanced open circuit voltage (V_OC) of 784 mV. The build-in voltage (V_bi) of 1.17 V and irradiation-dependent ideal factor (n) of 1.48 demonstrate enhanced heterojunction quality and suppressed defect recombination in the devices. The presented two-step annealing strategy and physical mechanism study will open new prospects for high-performance Sb₂S₃ solar cells.